ML20195G341
| ML20195G341 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 06/20/1988 |
| From: | Mroczka E NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, RTR-REGGD-01.097, RTR-REGGD-1.097 A02959, A04770, A2959, A4770, NUDOCS 8806270300 | |
| Download: ML20195G341 (18) | |
Text
,
1 O
MMES o.nor.i Orric s. seio.n street, Bernn. Connecticut l
sI E b s$tEw i
P.O. BOX 270 J C C,U.5',"," ~.
HARTFORD, CONNECTICUT 06141-0270 i
k L
(203) 665-5000 June 20, 1988 Docket No. 50-336 A04770 A02959 Re:
Supplement 1 to NUREG-0737 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C.
20555 Gentlemen:
Millstone Nuclear Power Station, Unit No. 2 Supplement I to NUREG-0737 Revision 2 to Reaulatory Guide 1.97 In a letter dated March 14, 1985,(I) the NRC Staff provided an interim report regarding the conformance status of Millstone Unit No. 2 with respect to Regulatory Guide 1.97, Revision 2.
This report indicated that Northeast Nuclear Energy Company's (NNEC0's) positions on Regulatory Guide 1.97 were acceptable to the NRC Staff except for certain items for whick2)further justificatir was requested.
In a letter dated August 7,
- 1986, NNEC0 provided the.equested additional information.
In the letter dated March 14, 1985, the NRC Staff listed a number of Category 2 variables for which NNEC0 does not have environmentally qualified instrumentation at Millstone Unit No. 2.
In recent telephone coaversations, the Staff discussed these variables with NNECO and requested that NNEC0 provide information as to why environmentally qualified instrumentation is not
{
necessary.
NNEC0 hereby provides the attached additional information in accordance with the Staff request.
The Staff also requested information on three other Regulatory Guide 1.97 variables (i.e.,
containment heat removal, pressurizer heater status, and steam generator wide range level). Additional information pertaining to these variables is also included in the attachment.
(1)
J. R. Miller letter to W. G. Counsil, "Request for Additional Information on Emergency Response Capability - Conformance to R. G.1.97 Rev. 2 for Hillstone Unit No. 2," dated March 14, 1985.
(2) 3.
F.
Opeka letter to A.
C.
- Thadani, "Revision 2 to Regul atory Guide 1.97," dated August 7, 1986.
8806270300 880620 PDR ADOCK 0D00033S
,O P
D U.S. Nuclear Regulatory Commission A04770/A02959/Page 2 June 20, 1988 If you have any questions, please contact us.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY AI Senior Vice Pr// ' dent E. Jf Mroczka esi Attachment cc:
W. T. Russell, Region I Administrator D. H. Jaffe, NRC Project Manager, Millstone Unit No. 2 W. J. Raymond, Senior Resident Inspector, Millstone Unit Nos. 1, 2 and 3 i
I l
\\
l Docket No. 50-336 I
A04770 l
A02959 1
1
\\
l l
Attachment Millstone Nuclear Power Station, Unit No. 2 Response to Request for Information Revision 2, Regulatory Guide 1.97 i
June 1988
'l Attachment A04770/A02959/Page 1 June 20, 1988 Millstone Nuclear Power Station, Unit No. 2 Response to Request for Information Revision 2. Reaulatorv Guide 1.97 NRC Staff Ouestion Provide a justification as to why the following Category 2 variables do not need environmentally qualified instrumentation at Millstone Unit No. 2.
NNEC0 Response 1)
Contitinment Sumo Water level -- Narrow Ranae (B-12b)
Information as to why this variable need not be environmentally August 7,1986gnprovidedtotheSgffbyNNEC0inlettersdated qualified has and June 15, 1987 These letters provifed the result: of a comparison between Regulatory Guide 1.97, Revis ion 2, and instrumentation at Millstone Unit No. 2 in tabular form.
As stated in those letters and hereby amplified, the narrow range sump level instruments are utilized during normal operation to monitor the normal containment sump.
This sump is relatively small and along with the trenches that lead to it would hold approximately one thousand gallons of water.
The narrow range level instrument provides level indication and alarms to alert the operator to-manually operate the sump pumps.
During a design basis event, the sumps would fill relatively quickly, rendering the narrow range level instrument useless. The operators would not utilize the sump pumps in order to avoid transferring contaminated water outside the containment.
The wide range containment water level instrumentation (B-12a),
which is environmentally qualified, provides the water level monitoring function during an accident situation.
(See Note 43, l
August 7, 1986 and June 15, 1987 ietters.)
2)
Residual Heat Removal (RHR) System Flow (D-1) i 1
As described in our August 7,1986 and June 15, 1987 letters, RHR l
pump motor ammeter readings, provided in the control room, are utilized as a backup to flow indication.
The ammeter scale for the l
RHR pump motors (Low Pressure Safety Injection pumps) is from 0 to 100 amperes.
The reading for normal RHR system operation is approximately 20 amperes.
Technical specification surveillance (1)
J. F. Opeka letter to A. C. Thadani, "Revision 2 to Regulatory Guide 1.97," dated August 7, 1986.
(2)
E. J. Mroczka letter to the U.S. Nuclear Regulatory Commission, "Revision 2 to Regulatory Guide 1.97," dated June 15, 1987.
Attachment A04770/A02959/Page 2 June 20, 1988 testing requires that system performance be evaluated and verified to meet requirements on a regular basis throughout the life of the plant.
This testing ensures the proper operation and condition of the pumps and piping and confirms that the system flow rates meet the design basis.
This must be done to satisfy technical specification operability requirements.
If the flow meters are not available, indicatit n of proper system operation is provided by the ammeter readings.
The operators, from experience, know generally what a proper amrater reading should be.
The ammeters are located in a mild envircnment not affected by accident conditions.
NNEC0 has concluded that surveillance
- testing, valve lineup verifications, pump motor ammeters, and redundancy (two separate and redundant trains) all ensure that the RHR system will perform its intended function. Therefore, pump motor ammeters are sufficient to keep the operators knowledgeable of the proper functions of the RHR system.
(See also Note 35, August 7,
1986 and June 15, 1987 letters.)
3)
RHR Heat Exchancer Outlet Temoerature (D-2)
The most important indicator of RHR system performance is RCS temperature. Technical specification surveillance testing and valve lineup verification ensure that system operability requirements are met.
Trending of RCS temperatum verifies that the RHR system is performing its intended function.
This is consistent with the philosophy of the symptom-oriented procedures that focus on meeting objectives (i.e., satisfying critical safety functionQ rather than simply looking at isolated and secondary indicators.
NNEC0 has concluded that adequate environmentally qualified instrumentation is available to verify that the RHR system is performing its intended function.
(See Note 38, August 7, 1986 and June 15, 1987 letters.)
4)
Safety In.iection (Accumulator) Tank Level (D-3a) and Pressure (D-3b)
The pressure and level indication for the safety injection tanks are important during normal operation to verify the operability of the system.
This is supported by valve lineup verifications.
This indication is not needed during and following an accident for the following reasons:
o They provide no automatic functions.
o No significant operator actions are based on their indication.
o This system is passive and functions early in an accident (1.0CA).
Attachment A04770/A02959/Page 3 June 20, 1988 During a large break LOCA, for which the safety injection tanks were installed, discharge of the tanks occurs within approximately 20 seconds.
Rapid reflood of the core is the most important function of the system.
There is typically no time for operator action. For all accidents RCS pressure will indicate whether or not tank discharge was called for.
Surveillance testing and valve lineup verification ensures system operability.
Redundancy protects against unanticipated failures and RCS pressure provides indication as to whethec or not the system was called upon.
NNEC0 has concluded that ade?nte environmentally qualified instrumentation is available to ensure the safety injection tanks perform their intended function.
(See Note 32, August 7, 1986 and June 15, 1987 letters.)
5)
Flow in the Hiah Pressure Safety In.iection System (D-6), Lqw Pressure Safety In.iection System (D-7), Containment Sorav System (D-22)
Similar to the discussion in Item 2 above, HPSI, LPSI and CS pump motor ammeter readings, located in the control room, provide a backup to flow indication.
Technical specification surveillance testing requires that system performance be evaluated and verified to meet requirements on a regular basis throughout the life of the plant.
This testing ensures the proper operation and condition of the pumps and piping and confirms that the gstem flow rates meet the design basis.
This must be done to satisfy technical specification operability requirements.
During an accident, operators verify that a Safety Injection Actuation Signal has occurred and that all Engineered Safety features components have properly responded (i.e.,
on/off, open/ closed).
If the flow meters are not available, pump motor ammeter readings provide this indication.
The meter scales for the HPSI, LPSI and CS pump motors are from 0 to 100 amperes. The normal reading for these pumps is approxiinately 20 amperes.
Surveillance testing and valve lineup verifications ensure system operability.
System redundancy protects against unanticipated failures and pump ammeters (located in mild environments) provide adequata backup indication of proper operation.
(See Note 35, August 7, 1986 and June 15, 1987 letters.)
6)
Containment Atmosohere Teocerature (D-24)
The key variable in assessing the '.ondition of containment during or after an accident is containment pressure.
Performance of the containment air recirculation ard cooling system (CARCS) and the containment spray system is monitored via containment pressure indication.
Containment pressure is recognized as the critical parameter with respect to maintaining containment integrity.
Corrective actions specified in E0P 2540, "Functional Recovery" and E0P 2540E "Functional Recovery of Containment Integrity" are based i
Attachment A04770/A02959/Page 4 June 20, 1988 I
on assessments of containment pressure specifically.
Containment I
temperature can be used as a support indication for diagnosis.
Therefore, NNEC0 has concluded that having this instrument as a Category 3, "hign quality, off-the-shelf instrument" powered from a I
reliable power supply is appropriate.
(See Note 41, August 7, 1986 l
and June 15, 1987 letters.)
l 7)
Makeuo (Charainal Flow-In (0-26), Letdown Flow-Out (0-27),
Volume Control Tank Level (D-28)
The charging pumps at Millstone Unit No. 2 are positive displacement pumps.
If the pumps are running, they are pumping a constant volume of water.
Therefore, charging flow is simply a function of how many pumps are running times 44 gallons per minute.
If the charging system pressure is greater than the reactor coolant syste and all the valves are open, then flow should be present.
Pressuricer level and differential pressure across the letdown filters provide backup indication for the letdown flow indication.
On a safety injection actuation signal, charging pump suction changes from the Volume Control Tank (VCT) to the discharge of the Boric Acid pumps (or the Boric Acid Storage Tanks).
Since the VCT is isolated, level indication is not required.
NNEC0 believes that there is adequate environmentally qualified instrumentation to monitor CVCS operation during an accident.
(See Notes 35 and 37, August 7, 1986 and June 15, 1987 letters.)
8)
Component Coolina Water Temperature to ESF System (0-29)
Component Coolina Water Flow to ESF Sv.siqm (D-30)
Component cooling water to ESF systems is provided by Reactor Building Closed Cooling Water (RBCCW) at Millstone Unit No. 2.
The ability of this system to remove heat from ESF systems and components was addressed during the design of the system.
Surveillance testing and valve lineup verification ensure that RBCCW meets the operability requirements of the technical specifications.
The system is redundant and ammeter readings on the main control board (located in a mild environment) provide an indication of proper pump operation.
The pump motor ammeter scales are from 0 to 100 amperes with a "normal" reading of approximately 40 amperes for the RBCCW pump motors.
(See the write-up for Item 2, RHR System Flow) 9)
Status of Standby Power (D-34)
All indication associated with monitoring standby power supplies is located in a mild environment and therefore is adequately qualified for the environment.
(See Note 22, August 7, 1986 and June 15, 1987 letters.)
Attachment A04770/A02959/Page 5 June 20, 19R NRC Staff Question In addition, the NRC Staff requested that NNEC0 provide additional information with respect to the following 3 Regulatory Guide 1.97 Revision 2 variables.
NNEC0 Response 1)
Containment Heat Removal (D-23)
Regulatory Guide 1.97 recommends "plant specific" Category 2
instrumentation for this variable. The Regulatory Guide provides no additional specific guidance for the recommended instrumentation.
As this is classified as a Type D variable, the purpose of the instrumentation is to "monitor the operation" of heat removal by the containment fan heat removal system.
The function of the containment air recirculation and cooling system (CARCS) at Millstone Unit No. 2 is to remove heat from the containment atmosphere during normal operation and accident conditions.
In the event of a LOCA, the system provides a means of cooling the containment atmosohere to reduce the containment building p'ressure and thus reduce the leakage of airborne and gaseous radioactivity.
The CARCS is independent of the safety injection and containment spray systems.
It is sized such that, following a LOCA, three of the four containment air recirculation units limit the containment pressurt to less than the containment design pressure even if the conta nment spray system does not operate. The components of.the CARCS are designed to operate in the most severe post-accident environment as described in Section 6.1 of the Millstone Unit No. 2 FSAR.
The ability of the CARCS to perform its intended function is addressed in the actual design of the system it: elf.
The system was designed such that only 3 of the 4 units are required to cool the containment following a design basis event.
Surveillance testing ensures that the CARCS and its corresponding support systems meet their operability requirements.
The primary means to assess the performance of the CARCS is containment pressure (C-11, environmentally qualified).
The heat sink for the CARCS is RBCCW.
Instrumentation within RBCCW is available to the operator to monitor the operation of the CARCS during normal as well as post-accident conditions.
Temperaturesensors(T-6031,T-6032,T-6033)atthedfschargeofthe three RBCCW heat exchangers have a range of 0-200 F and provide indication of the RBCCW tercerature entering each of the four containment air recirculation fan coolers.
Temperatgre sensors (T-6082, T-6086, T-6090, T-6093), with a range of 0-200 F, are also available to measure the RBCCW flow temperature at the exit of the containment air recirculation fan coolers.
Flow elements (FE-6081, i
FE-6085, FE-6089, FE-6094) are available at the exit of the fan coolers, with a range of 0-3000 gpm, to directly monitor RBCCW flowrate through each of the fan coolers.
The above instrumentation has indication in the control room and allows the operator to l
Attachment A04770/A02959/Page 6 June 20, 1983 monitor the operation of the CARCS while providing sufficient information for the operator, if desired, to determine the heat removal capability of each of the containment air recirculation fan coolers.
- However, these instruments are not environmentally qualified. They are powered from reliable power supplies.
NNECO believes that system design, surveillance testing, valve lineup verification, redundancy, and existing environmentally l
qualified instrumentation are adequate to monitor containment heat removal.
2)
Pressurizer Heater Status (D-12) l As specified in Note 12 to NNEC0's letter dated June 15, 1987, the pressurizer heater status is monitored by breaker status indicating lights.
As detailed in the cover lettar (June 15, 1987) NNECO intends to install a meter on the main control board for each bank of proportional heaters which will indicate the heater banks response to the pressurizer pressure controller signal.
This issue is being addressed as part of the control room design review l
process.
The most recent schedule for implementation l
corrections was submitted to the NRC Staff on May 18, 1988.( g CRDR l
1 3)
Steam Generator Wide Ranae level (0-16) l This issue was discussed in the cover letter dated June 15, 1987.
If NNEC0 decides to replace the steam generators (SG) at Millstone j
Unit No. 2, we plan to include wide range steam generator level indication.
The decision as to whether or not to replace the SGs is expected within the next few years depending on the performance of the existing SGs.
We do not believe it is prudent at this time to make a decision about installation of this instrumentation in the case where the SGs l
are not replaced.
We believe it is more appropriate to make that decision in concert with our SG replacement decision and the CRDR l
program.
We intend to periodically (e.g., annually) keep the staff informed of our plans to replace the SGs at Millstone Unit No. 2 and to install wide range steam generator level indication.
1 (3)
E.
J.
Mroczka letter to the U.S.
Nuclear Regulatory Commission, "Correction of the Human Engineering Discrepancies," dated May 18, 1988.
E'M UEES General Offices
- Selden Street, Berkn, Connecticut ART O CONNECTICUT 06141-0270 June 20, 1988 Docket No. 50-336 A04770 A02959 Re:
Supplement 1 to NUREG-0737 U.S. Nuclear Regulatory Commission Attn:
Document Control Desk Washington, D.C.
20555 Gentlemen:
Millstone Nuclear Power Station, Unit No. 2 Supplement 1 to NUREG-0737 Revision 2 to Reaulatory Guide 1.97 In a letter dated March 14,1985,(I) the NRC Staff provided an interim report regarding the conformance status of Millstone Unit No. 2 with respect to Regulatory Guide 1.97, Revision 2.
This report indicated that Northeast Nuclear Energy Company's (NNECO's) positions on Regulatory Guide 1.97 were acceptable to the NRC Staff except for certain items for whick2)further justification was requested.
In a letter dated August 7,
- 1986, NNEC0 provided the requested additional information.
In the letter dated March 14, 1985, the NRC Staff listed a number of Category 2 variables for which NNEC0 does not have environmentally qualified instrumentation at Millstone Unit No. 2.
In recent telephone conversations, the Staff discussed these variables with NNECO and requested that NNEC0 provide information as to why environmentally qualified instrumentation is not necessary.
NNEC0 hereby provides the attached additional information in accordance with the Staff request.
The Staff also requested information on three other Regulatory Guide 1.97 variables (i.e.,
containment heat removal, pressurizer heater status, and steam generator wide range level).
1 i
(1)
J. R. Miller letter to W. G. Counsil, "Request for Additional Information on Emergency Response Capability - Conformance to R. G.1.97 Rev. 2 for Millstone Unit No. 2," dated March 14, 1985.
(2)
J.
F.
Opeka letter to A.
C.
- Thadani, "Revision 2 to Regulatory Guide 1.97," dated August 7, 1986.
^
i U.S. Nuclear Regulatory Commission A04770/A02959/Page 2 June 20, 1988 O (Additional information pertaining to these variables is also included in the 5
attachment.
- [
If you have any questions, please contact us.
<9 Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY E. J. Mroczka Senior Vice President Attachment cc:
W. T. Russell, Region I Administrator D. H. Jaffe, NRC Project Manager, Millstone Unit No. 2 W..). Raymond, Senior Resident Inspector, Millstone Unit Nos. 1, 2 and 3
Docket No. 50-336 A04770 A02959 Attachment Millstone Nuclear Power Station, Unit No. 2 Response to Request for Information Revision 2, Regulatory Guide 1.97 Jun 1988 i
i Attachment A047/0/A02959/Page 1 June 2's, 1988 Millstone Nuclear Power Station, Unit No. 2 Response to Request for Information Revision 2. Reaulatory Guide 1.97 NRC Staff _0uestion Provide a justification as to why the following Category 2 variables do not need environmentally qualified instrumentation at Millstone Unit Ho. 2.
(NECO Response 1)
Containment Sumo Water Level -- Narrow Ranae (B-12b)
Information as to why this variable need not be environmentally August 7,1986gn provided to the Sgff by NNECO in letters dated qualified has and June 15, 1987.
These letters provided the i
results of a comparison between Regulatory Guide 1.97, Revision 2, and instrumentation at Millstone Unit No. 2 in tabular form.
As stated in those letters and hereby amplified, the narrow range sump 1evel instruments are utilized during normal operation to monitor the normal containment sump.
This sump is relatively small and l
along with the trenches that lead to it would hold approximately one thousand gallons of water.
The narrow range level instrument provides level indication and alarms to alert the operator to manually operate the sump pumps.
During a design basis event, the sumps would fill relatively quickly, rendering the narrow range level instrument useless. The operators would not utilize the sump punps in order to avoid transferring contaminated water outside the i
centainment.
The wide range containment water level instrumentation (B-12a),
which is environmentally qualified, provides the water level monitoring function during an accident situation.
(See Note 43, August 7, 1986 and June 15, 1987 letters.)
2)
Residual Heat Removal JRHR1 System Flow (D-1)
As described in our August 7, 1986 and June 15, 1987 letters, RHR pump motor ammeter readings, provided in the control room, are utilized as a backup to flow indication.
The ammeter scale for the RHR pump motors (Lc.w Pressure Safety Injection pumps) is from 0 to 100 amperes.
The reading for normal RHR system operation is approximately 20 amperes.
Technical specification surveillance (1)
J. F. Opeka letter to A. C. Thadani, "Revision 2 to Regulatory Guide 1.97," dated August 7, 1986.
(2)
E. J. Mroczka letter to the U.S. Nuclear Regulatory Commission, "Revision 2 to Regulatory Guide 1.97," dated June 15, 1987.
i Attachment A04770/A02959/Page 2 June 20, 1988 i
testing requires that system performance be evaluated and verified to meet requirements on a regular basis throughout the Mfe of the plant.
This testing ensures the proner operation and condition of the pumps and piping and confirms that the system flow rates meet the design basis.
This must be done to satisfy technical specification operability requirements.
If the flow meters are not available, indication of proper system operation is provided by the ammeter readings.
The operators, from experience, know generally what a proper ammeter reading should be.
The ammeters are located in a mild environment not affected by accident conditions.
NNEC0 has concluded that surveillance
- testing, valve
!ineup verifications, pump motor ammeters, and redundancy (two separate and redundant trains) all ensure that the RHR system will perform its intended function. Therefore, pump motor ammeters are sufficient to keep the operators knowledgeable of the proper functions of the RHR system.
(See also Note 35, August 7,
1986 and June 15, 1987 M
letters) 3)
RHR Heat Exchanaer Outlet Temperature (D-2) mwad-previoastyd in th mition WONFtFaTThe most important indicator of RHR system performance is RCS temperature.
Technical specification surveillance testing and vahe lineup verification ensure that system operability requirements are met.
Trending of RCS temperaturo verifies that the RHR system is performing its intended function.
This is consistent with the philosophy of the symptom-oriented procedures that focus on meeting objectives (i.e., satisfying critical safety functions) rather than simply looking at isolated and secondary indicators.
NNEC0 has concluded that adequate environmentally qualified instrunentation is available to verify that the RHR system is performing its intended function.
(See Note 38, August 7, 1986 and June 15, 1987 letters)
(.--
A 4)
Safety In.iection (Accumulator) Tank level (D-3a) and Pressure (D-3b)
The pressure and level indication for the safety injection tanks are important during normal operation to verify the operability of the system.
This is supported by valve lineup verifications.
This indication is not needed during and following an accident for the following reasons:
o They provide no automatic functi s,
Nosignificantoperatoractionsarebasedontheirindicatih o
o This Ay tem is passive and functions early in an accident (LOC 1
l Attachment A04770/A02959/Page 3 June 20, 1988 During a large break LOCA, for which he safety injection tanks were installed, discharge of the tanks occurs within approximately 20 seconds.
Rapid reflood of the core is the most important function of the system.
There is typically no time for operator action. For all accidents RCS pressure will indicate whether or not tank discharge was called for.
Surveillance testing and valve 15eup verification ensures system operability.
Redundancy protects against unanticipated failures and RCS pressure provides indication as to whether or not the system was called upon.
NNEC0 has concluded that adequate environmentally qualified instrumentation is available to ensure the safety injection tanks perform their intended function.
(See Note 32, August 7, 1985 and June 15, 1987 letters Y
5)
Flow in the Hioh Pressure Safety In.iection System (D-6), Lgy Pressure Safety In.iection System (D-7), Containment Soray System (0-22)
Similar to the discu sTon in Item 2 above, HPSI, LPSI and CS pump motor ammeter readt s loc ted in the control room, provide a backup o
to flow indicatio.
'T - nical specification surveillance testing requires that syste performance be evaluated and verified to meet requirements on a regular basis throughout the life of the plant.
This testing ensures the proper operation and condition of the pumps and piping and confirms that the system flow rates meet the design basis.
This must be done to satisfy technical specification operability requirements.
During an accident, operators verify that Safety Injection Actuation Signal has occurred and that all Engineered Safety Features components have properly respo ied (i.e.,
on/off, open/ closed).
If the flow meters are not a..silable, pump motor ammeter readings provide this indication.
The meter scales for the HPSI, LPSI and CS pump motors are from 0 to 100 amperes. The normal 1
reading for these pumps is approximately 20 amperes.
M*mitimIE40 dht Mrveillance testing and valve lineup verifications ensure system operability.
System redundancy protects against unanticipated failures and pump ammeters (located in mild environments) provide adequate backup indication of prc,per operatien.
(See Note 35, August 7, 1986 and June 15, 1987 1atters 6)
Containment Atmosobere Temoerature (D-24)
The key variable in assessing the condition of containment during or after an accident is containment pressure.
Performance of the containment air recirculation and cooling system (CARCS) and the containment spray system is monitored via containment pres.sure indication.
Containment pressure is recognized as the critical l
parameter with respect to maintaining containment integrity.
Corrective actions specified in E0P 2540, "Functional Recovery" and E0P 2540E "Fur.ctional Recovery of Containment Integrity" are based
Attachment A04770/A02959/Page 4 June 20, 1988 on assessments of containment pressure specifically.
Containment j
temperature can be used as a support indication for diagnosis.
i Therefore, NNEC0 has concluded that having this instrument as a Category 3, "hi9h quality, off-the-shelf instrument" powered from a reliaolo power supply is appropriate.
(See Note 41, August 7,1986 and June 15, 1987 lettersj 7)
Makeuo (Charainal Flow-In (D-26), Letdown Flow-0qt. (D-27),
Volume Control Tank Level (D-28)
The charging pumps at Millstone Unit No. 2 are positive displacement numps.
If the pumps are running, they are pumping a constant volume of water. Therefore, charging flow is simply a function of how many pumps are running times 44 gallons per minute.
If the charging system pressure is greater than the reactor coolant system and all the valves are open, then flow should be present.
Pressurtzer level and differential pressure across the letdown filters provide backup indicatien for the letdown flow indication.
On a safety injection actuation signal, charging pump suction changes from the Volume control Tank (VCT) to the discharge of the Boric Acid pumps (or the Boric Acid Storage Tanks).
Since the VCT is isolated, level indication is not required.
NNEC0 believes that there is adequate environmentally qualified instrumentation to monitor CVCS operation during an accident.
(See Notes 35 and 37, August 7, 1986 and June 15, 1987 letters 4 A
8)
Comoonent Coolina Water Temoerature to ESF System (D-29)
Comoonent Coolina Water Flow to ESF System (D-30)
Component cooling water to ESF systems is provided by Reactor Building Closed Cooling Water (RBCCW) at Hillstone Unit No. 2.
The ability of this system to remove heat from ESF systems and components was sddressed during the design of the system.
Surveillance testing and valve lineup verification ensure that RBCCW meets the operability requiremeats of the technical specifications.
The system is redundant and ammeter readings on the main control board (located in a mild environment) provide an indication of proper pump operation.
The pump motor ammeter scales are from 0 to 100 amperes with a "normal" reading of approximately 40 amperes for the RBCCW pump motors.
(See the write-up for Item 2, RHR System Flow) 9)
Status of FM@v Powe- (9-34)
All indication E.ssociated with monitoring standby power supplies is located in a mild environment and therefore is adequately qualified for the environment.
(See Note 22, August 7, 1986 and June 15, 1987 letters) h
Attachment A04770/A02959/Page 5 June 20, 1988 NRC Staff Question In addition, the NRC Staff requested that NNEC0 provide additional information with respect to the following 3 Regulatory Guide 1.97 Revision 2 variables.
NNEC0 Resoonse 1)
Containment HNt Removal (0-23)
Regulatory Guide 1.97 recommends "plant specific" Category 2 instrumentation for this variable.
The Regulatory Guide provides no additional specific guidance for the recommended instrumentation.
As this is classified as a Type D variable, the purpose of the instrumentation is to "monitor the operation" of heat removal by the containment fan heat removal system.
The ft.netion of the containment air recirculation and cooling system (CARCS) at Millstone Unit No. 2 is to remove heat from the containment atmosphere during normal operation and accident conditions.
In the event of a LOCA, the system provides a means of cooling the containment atmosphere to reduce the containment building pressure and thus reduce the leakage of airborne ar.d gaseous radioactivity.
The CARCS is independent of the safety injection and containment spray systems.
It is sized such that, following a LOCA, three of the four containment air recirculation units limit the containment pressure to less than the containment design pressure even if the containment spray system does not operate.
The components of the CARCS are designed to operate in the most severe post-accident environ n s described in Section 6.1 of the Millstone Unit No. 2 FSAR.
The ability of the CARCS t-rform its intended function is addressed in the actual design of the system itself. The system was designed such that only 3 at 4 units are required to cool the contair, ment following a design basis event.
Surveillance testing ensures that the CARCS and its corresponding support systems meet their operability requirements.
The primary means to assess the performance of the CARCS is containment pressure (C-11, environmentally qualified).
The heat i
sink for the CARCS is RBCCW.
Instrumentation within RBCCW is available to the operator to monitor the operation of the CARCS during normal as well as post-accident conditions.
Temperaturesensora(T-6031,T-6032,T-6033)atthedfschargeofthe three RBCCW heat exchangers have a range of 0-200 F and provide i
indication of the RBCCW temperature entering each of the four containment air recirculation fan coolers.
Temperatfire sensors (T-6082, T 6086, T-6090, T-6093), with a range of 0-200 F, are also available to measure the RBCCW flow temperature at the exit of the containment air recirculation fan coolers.
Flow elements (FE-6081, FE-6085, FE-6089, FE-6094) are available at the exit of the far.
coolers, with a range of 0-3000 gpm, to directly monitor RBCCW flowrate through each of the fan coolers. The above instrumentation has indication in the control room and allows the operator to
l s.
Attachment A04770/A02959/Page 6 June 20, 1988 monitor the operation of the CARCS while providing sufficient information for the operator, if desired, to determine the heat removal capability of each of the containment air recirculation fan I
coolers.
- However, these instruments are not environmentally
[
qualified. They are powered from reliable power supplies.
NNEC0 believes tht system design, surveillance testing, valve lineup verificathn, redundancy, and existing environmentally qualified instrumentation are adequate to monitor containment heat j
removal.
l 2)
Pressuri7er Heater Status (D-12)
As specified in Note 12 to NNEC0's letter dated June 15, 1587, the pressurizer heater status is monitored by breaker status indicating lights.
As detailed in the cover letter (June 15, 1987) NNECO intends to install a meter on the main control board for each bank of proportional heaters which will indicate the heater banks response to the pressurizer pressure controller signal.
This issue is being addressed as part of the control room design review process.
The most recent schedule for implementation CRDR I
corrections was submitted to the NRC Staff on May 18,1988(3pf 3)
Steam Generator Wide Ranae__ Level (0-16)
This issue was di sIe the cover letter dated June 15, 1987.
If NNEC0 decides to replace the steam generators (SG) at Millstone Unit No.
2, we MM include wide range steam generator level indication.
The decision as to whether or not to replace the SGs is expected within the next few years depending on thep the existin Est-g gg et-ou We do not believe it is prudent at this(time to make a decision about installation of this instrumentation 4 We believe it is more appropriate to make that decision in concert with our SG replacement decision and the CRDR program.
We intend to periodically (e.g.,
annually) keep the staff informed of our plans to replace the SGs at Millstone Unit No. 2 and to install wide range steam generator level indication.
(3)
E.
J.
Mroczka letter to the U.S.
Nuclear Regulatory Commission, "Correction of the Human Engineering Discrepancies," dated May 18, 1988.
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